1. Field of the Invention (Technical Field)
The present invention relates to methods of preparing sulfonic acid-terminated polyisobutylenes, particularly sulfonated telechelic polyisobutylenes (STPs).
2. Background Art
Telechelic ionomers, which bear ionic groups only at the ends of non-polar polymer chains, have received enormous interest as they display unique properties in bulk and solutions. Interest in the properties of ionomer solutions is justified by the many potential applications including viscosity controlling agents and gelling agents for tertiary oil recovery. The presence of ionic groups, specifically at the ends of polymer chains of nonpolar nature, has significant effect upon polymer properties as a consequence of ionic aggregation.
In a series of publications over a decade, J.P. Kennedy and others have demonstrated the importance of both linear .alpha., .omega.- difunctional and trifunctional star STP ionomers. To date, the STP ionomers represent the most versatile telechelic ionomers and there still persists a great demand for such ionomers. For example, these ionomers are of interest for theoretical purposes, as viscosity controlling agents, as elastomers, and as thermoplastics. To date, however, the preparation of STPs is neither simple nor economical.
STPs are presently synthesized by either of the multi-step procedures shown in FIGS. 1 and 2. Both are unsatisfactory.
The prior art process of FIG. 1 requires a laborious and expensive dehydrochlorination reaction of the prepolymers end-capped with tert-chloro groups. References presenting the procedure of FIG. 1 include Kennedy and Storey, "New Polyisobutylene-Based Ionomers: Synthesis and Model Experiments," Org. Coat. Appl. Polym. Sci. 46:182-85 (1981) and Mohajer, et al., "New Polyisobutylene Based Ionomers: 3. Further Mechanical and Structural Studies," Polym. Bull. 8:47-54 (1982).
The prior art process of FIG. 2 eliminates the dehydrochlorination reaction but still requires the preparation and processing of tert-chloro terminated prepolymer. References presenting the procedure of FIG. 2 include Storey, et al., "Sulfonation of tert-Alkyl Chlorides: Application to the tert-chloride-Terminated Polyisobutylene System," J. Polym. Sci.: Part A: Polym. Chem. 29:317-25 (1991) and Storey, et al., "Sulfonation of tert-Alkyl Chlorides: Application to the tert-chloride-Terminated Polyisobutylene System," ACS Polym. Prepr. 1991:593-94.
In a 1992 publication, Kennedy admits that efforts to that date to end-quench living polyisobutylene without creating tert-chloro groups had been unsuccessful with various quenching agents such as esters, ketones, ethers, anhydrides, dimethylacetamide, dimethylsulfoxide, and alkyl aluminums. Kennedy, et al., Designed Polymers by Carbocationic Macromolecular Engineering: Theory and Practice 142-43 (1992).
Faust and Kennedy, "Living Carbocationic Polymerization: III. Demonstration of the Living Polymerization of Isobutylene," Polym. Bull. 15:317-23 (1986), discloses living carbocationic polymerization of isobutylene and quenching the living recipe with methanol and other reagents such as amines or by increasing the temperature above the decomposition of the propagating ester complex. See also Faust and Kennedy, "Living Carbocationic Polymerization: IV. Living Polymerization of Isobutylene," J. Polym. Sci.: Part A: Polym. Chem. 25:1847-69 (1987).
Kaszas, et al., "Electron-pair Donors in Carbocationic Polymerization: I. Introduction into the Synthesis of Narrow Molecular Weight Distribution Polyisobutylenes," Polym. Bull. 20:413-19 (1988) discloses the preparation narrow molecular weight distribution telechelic polyisobutylenes with tert-chloro end groups.
Kennedy, "End Quenching and End-Functionalization in Living Carbocationic Polymerization," Polym. Prepr. 33(1):903 (1992) and Ivan, et al., "Living Carbocationic Polymerization. III.: One-Pot Synthesis of Allyl-Terminated Linear and Tri-Arm Star Polyisobutylenes and Epoxy and Hydroxy-Telechelics Therefrom," J. Polym. Sci., Part A: Polym. Chem. 28:89-104 (1990) disclose one-pot end quenching of living polymerization of isobutylene, specifically the synthesis of various linear and three-arm star allyl-terminated telechelic polyisobutylenes.
The present invention is of a process of producing STPs without creating tert-chloro terminated groups and without the need for dehydrochlorination. The present invention is much simpler and more economical than prior art methods.